View Full Version : High suction pressure and high head due to overfeeding expansion valve?

27-05-2017, 12:08 AM
Did a AC job a Saab 9-5 today. Was low on ref so pulled a vacuum and weighted in the correct charge for it. Still did not work ok. Head was somewhat high at 225 psi for 75 ambient and the suction was way high at 60 psi. Fans working and condenser is clean. It's not over charged so could this be a stuck open expansion valve or something with the variable deplacement compressor thingy?

27-05-2017, 01:39 AM
Sweden, what RPM when taking readings?
Did you evacuate high & low side of system?

27-05-2017, 10:08 AM
Readings at idle. I was alone and car has drive by wire throttle so I would have to mess with the pedal to raise it. Yes I evacuated from both sides. I used a Bluvac meter and pulled down to 1200 microns and was holding 1500 microns 10 mins later so that part is ok.

27-05-2017, 11:05 AM
Need to run engine faster to get suction down as well as discharge will lower with more air over condenser.
Then you can see what's happening with pressures to evaluate cooling performance.
Try 1500 rpm minimum.

27-05-2017, 11:36 AM
Have you cleaned condensor with chemical they can look clean but in fact are dirty.

charlie patt
27-05-2017, 06:22 PM
When you gases it did you put it in as liquid suction stub on a stable right above the comp line ??????

27-05-2017, 11:57 PM
Ok I will have another go at this car so I will clean condenser and do some readings at 1500+. I'm sorry Charlie but I dont get all of what you're saying. English is not my native language. I charged here up completely in gas state at low side if that's what you're saying.

charlie patt
28-05-2017, 06:17 PM
If charged as a liquid on low side with suction stubbs so close to comp the comp will be in trouble suction is far to high should be half of that sometimes if the little car comps been empty for a while the vanes stick a bit if you run it up the road and it don't improve on suction you need a comp

28-05-2017, 07:31 PM
Ok now I get it. Thanks for pointing that out. I had that Saab come by today and things looked better at 35 psi at 1500 rpms but I'm still not impressed with 54F from the vents.

28-05-2017, 07:45 PM
Look like good pressures for R22 lol

28-05-2017, 09:15 PM
Its the death penalty for using R22 in sweden. We will soon loose R410 too. Its R32 on new residential stuff and R1234yf on cars.

28-05-2017, 10:48 PM
Can you clarify which refrigerant you charged system.
Normally have to charge liquid for synthetic refrigerants so blend remains as designed.

28-05-2017, 11:01 PM
R134a is still used in older cars including this Saab. New cars are not allowed to be sold using R134a in European Union. Sorry for being unclear.

charlie patt
29-05-2017, 04:51 PM
Apart from German cars which are still on 134

30-05-2017, 12:34 AM
Until now they have been able to pay expensive fines for every sold car with R134a but I don't think they will get away with that any longer.